/**********
This library is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the
Free Software Foundation; either version 3 of the License, or (at your
option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.)

This library is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
more details.

You should have received a copy of the GNU Lesser General Public License
along with this library; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
**********/
// "liveMedia"
// Copyright (c) 1996-2018 Live Networks, Inc.  All rights reserved.
// MPEG-1 or MPEG-2 Video RTP Sources
// Implementation

#include "include/MPEG1or2VideoRTPSource.hh"

MPEG1or2VideoRTPSource *
MPEG1or2VideoRTPSource::createNew(UsageEnvironment &env, Groupsock *RTPgs,
                                  unsigned char rtpPayloadFormat,
                                  unsigned rtpTimestampFrequency) {
    return new MPEG1or2VideoRTPSource(env, RTPgs, rtpPayloadFormat,
                                      rtpTimestampFrequency);
}

MPEG1or2VideoRTPSource::MPEG1or2VideoRTPSource(UsageEnvironment &env,
                                               Groupsock *RTPgs,
                                               unsigned char rtpPayloadFormat,
                                               unsigned rtpTimestampFrequency)
        : MultiFramedRTPSource(env, RTPgs,
                               rtpPayloadFormat, rtpTimestampFrequency) {
}

MPEG1or2VideoRTPSource::~MPEG1or2VideoRTPSource() {
}

Boolean MPEG1or2VideoRTPSource
::processSpecialHeader(BufferedPacket *packet,
                       unsigned &resultSpecialHeaderSize) {
    // There's a 4-byte video-specific header
    if (packet->dataSize() < 4) return False;

    u_int32_t header = ntohl(*(u_int32_t *) (packet->data()));

    u_int32_t sBit = header & 0x00002000; // sequence-header-present
    u_int32_t bBit = header & 0x00001000; // beginning-of-slice
    u_int32_t eBit = header & 0x00000800; // end-of-slice

    fCurrentPacketBeginsFrame = (sBit | bBit) != 0;
    fCurrentPacketCompletesFrame = ((sBit != 0) && (bBit == 0)) || (eBit != 0);

    resultSpecialHeaderSize = 4;
    return True;
}

Boolean MPEG1or2VideoRTPSource
::packetIsUsableInJitterCalculation(unsigned char *packet,
                                    unsigned packetSize) {
    // There's a 4-byte video-specific header
    if (packetSize < 4) return False;

    // Extract the "Picture-Type" field from this, to determine whether
    // this packet can be used in jitter calculations:
    unsigned header = ntohl(*(u_int32_t *) packet);

    unsigned short pictureType = (header >> 8) & 0x7;
    if (pictureType == 1) { // an I frame
        return True;
    } else { // a P, B, D, or other unknown frame type
        return False;
    }
}

char const *MPEG1or2VideoRTPSource::MIMEtype() const {
    return "video/MPEG";
}

